The present invention relates to data communications, and more particularly to apparatus for configuring data communication networks including data modems.
In the past it has been common to manually strap a modem into a particular mode of operation or configuration. Strap-variable modem parameters include speed, multiport, half or full duplex, point-to-point or multipoint, central or remote modem, etc. Strap settings may also select a dynamic port allocation mode of operation or "dynaport." One example of dynaport operation is illustrated in U.S. Pat. No. 4,270,202 to Studdard et al., assigned to the assignee of the present application.
Increasing complexity of modem design has resulted in an increase in the number and complexity of straps to be set during manufacture and by the installer and/or operator to satisfy various modem user demands for differing configurations and uses of the modems. Further, it has often been necessary to deenergize the modem to complete strapping, thus resulting in lost data transmission time. In the past it has been possible to make very limited changes in the modem configuration, which are akin to strapping changes, by use of switches operated by, e.g., pushbuttons on the modem front panel to change modem speed in bits per second. Such switches are hard wired to the appropriate part of the modem's internal circuitry to effect a desired change.
In the past, it has been common to arrange modems in a network with a network controller. One such network is illustrated by U.S. Pat. No. 4,385,384, assigned to the assignee of the present application, entitled Modem Diagnostic and Control System, of Arthur H. Rosbury, et al., the disclosure of which is hereby incorporated by reference.
Typical prior art network control systems monitor modem status and operating parameters and transmit that information to the network controller. Also, it has been common for the network controller to be able to poll the modems on the network and command transmission to the network controller of status and parameter information. The network controller also has been used to receive indications of modem failure on the network and to command performance by a modem of selected testing routines and transmission of the results thereof to the network controller. This has been done in the past over a telemetry link using a slow data rate of, e.g., 75 bps and, e.g., FSK data transmission on a portion of the transmission link which is not being used for transmission of high speed data between data terminals. Display at the network controller of the status and configuration of remote modems on the network has thus been possible, along with display of the results of the command testing routine performed by the remote modem.
It has been found that it is often desirable to have the ability for modems of the transmission link to inquire of the status and configuration of other modems on the link and to initiate testing at the other modem, without the intervention of the network controller, or to be apprised of malfunction conditions at a particular remote modem without such intervention. It has also been found that the art is in need of a means of reconfiguring a modem without removing power to the modem and without interrupting data transmission. It is also desirable to be able to reconfigure and restrap remote modems on the same data link from a local site.
The present invention thus relates to a modem, e.g., contained in a data link which has input means on the external portion of the modem chassis, e.g., the front panel, and an accompanying display means. The input means and display means are coupled to a microprocessor or other suitable LSI circuit data processor having a stored memory. The memory may include electrically alterable nonvolatile programmable ROM, e.g., an ER 1400 made by General Instruments, or, alternatively, such an EAROM and a fixed ROM. The microprocessor or other suitable LSI circuit data processor can also be coupled to an external source of control signal input, e.g., a centrally located network controller, another modem on the data transmission link, or data terminal equipment (DTE) on the data link.
It is a feature of the present invention that strapping is implemented by use of a microprocessor contained within the modem and associated memory. The strapping microprocessor in conjunction with other microprocessors or LSI circuits within the modem establishes the configuration of the modem. The strapping microprocessor is operator-accessible at the site of the modem through an input and display section on, e.g., the front panel of the modem. By use of the front panel the operator can command display of the current strapping configuration, command implementation of certain preselected standard or user-designed strapping configurations, or make minor changes to the preselected standard or user-designed configurations. All of this can be done, as well, at the time of manufacture or installation to quickly and accurately establish the strapping configuration best suited to a given customer's intended usage of the modem. In addition, strapping can be modified modem-to-modem with the present invention. Other testing and monitoring functions can also now be accomplished from the front panel and modem-to-modem, without the need of intervention of a network controller or a DTE, however, these latter may also be used to command and monitor testing and status reports, or for the implementation of remote modem strapping changes. Modems on the data link can thus be quickly and accurately reconfigured, without removal of power to the modems in question and with very little or no interruption of data transmission.